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Coal Inspectorate | Alert | No.420 V 1 | 14 December 2022

Bulldozer drops into a void above a conveyor feed valve point

What happened?

A bulldozer working on a coal stockpile dropped into a void above a conveyor feed valve point.

How did it happen?

During preparation of the stockpile for train loading, the location of the feed valve was miscalculated.

The feed valve location was not available on the GPS system in the bulldozer.

External reference points used by bulldozer operators to locate the feed valves were inaccurate.

Coal taken through the feed valve to the load out bin created a rathole, because the void did not reach the stockpile surface.

The coal bridge above the void failed beneath the weight of the bulldozer (see Figures 1 and 2).

Key issues

  • The bulldozer operator did not have an accurate location for the feed valve in the stockpile.
  • The stockpile profile used as the visual aid for the location of the feed valve was incorrectly positioned during stockpile preparation.
  • Not all bulldozers in use on the stockpile were fitted with GPS units.


All Site Senior Executives should:

  • clearly demarcate stockpile feed valve locations on the surface of coal stockpiles.
  • have a system that manages movement of mobile equipment and personnel on coal stockpiles.
  • utilise the advice given in MDG 28: Safety requirements for coal stockpiles and reclaim tunnels when conducting risk assessments relevant to working on coal stockpiles.

All operators should:

  • confirm the location of feed valves under coal stockpiles before accessing the stockpile surface.
  • keep their machine outside the nominated distance from the feed valve.

Investigations are ongoing and further information may be published as it becomes available. The information in this publication is what is known at the time of writing.

We issue Safety Notices to draw attention to the occurrence of a serious incident, raise awareness of risks, and prompt assessment of your existing controls.

Authorised by Peter Newman - Chief Inspector – Coal

Contact: Stephen Smith, Regional Inspector of Mines , 0436 658 225

Issued by Resources Safety & Health Queensland

Safety: This information is issued to promote safety through experience. It is not to be taken as a statement of law and must not be construed to waive or modify any legal obligation.
Placement: Place this announcement on noticeboards and ensure all relevant people in your organisation receive a copy, understand the content, findings and recommendations as applicable to their operation. SSEs should validate that recommendations have been implemented.